Twice, long ago, Earth was completely covered in ice. This "Snowball Earth" may have led to more complex life. Evidence like dropstones proves the ice reached even warm areas.

Anyone living on Earth between 720 million and 635 million years ago probably would've needed a jacket. Geologists have long ...

An artist's conception of "Snowball Earth," when the planet was either completely or largely covered in ice hundreds of millions of years ago. Even the balmy tropics may have once been crushed by ...

This is a vicious cycle that on other planets may have left it covered in ice forever. Over time, however, the CO2 levels built up on the Earth from volcanic eruptions and other sources.

The Pleistocene glaciation contained at least 20 ice fluctuations within it, in which ice advanced and receded. Sometimes, up to 30% of Earth was covered in ice.. At times this included the better ...

Imagine the entire earth covered in ice. It’s not that far-fetched. It actually happened more than once. Was it because Anna got mad at Elsa? No, but the real reason is even cooler. Scientists only ...

So why isn’t the Earth covered in ice right now? It’s because we are in a period known as an “interglacial.” In an ice age, temperatures will fluctuate between colder and warmer levels.

Imagine the entire earth covered in ice. It’s not that far-fetched. It actually happened —more than once. Was it because Anna got mad at Elsa? No, but the real reason is even cooler. Scientists only ...

During ice ages, ice sheets like the one in Greenland have covered much of Earth's surface. (Image credit: Thor Wegner/DeFodi Images via Getty Images) This article was originally published at The ...

Even the balmy tropics may have once been crushed by colossal masses of ice. A severe ice age dominated Earth, some 720 to 635 million years ago, well before dinosaurs stalked the land. But it's ...

Geologists have long suspected that Earth's temperature dropped dramatically during this time, resulting in a frigid "Snowball Earth."But they've argued quite a bit about just how icy the planet ...

Anyone living on Earth between 720 million and 635 million years ago probably would've needed a jacket. Geologists have long suspected that Earth's temperature dropped dramatically during this ...